1. Technical Field
The present exemplary embodiment relates to a high-frequency member assembly with a waveguide wherein a choke structure is disposed near the waveguide in an attaching area between two high-frequency members attached to each other.
2. Description of Related Art
A high frequency device has a pair of high-frequency members attached to each other, and the members have respective waveguide portions communicating with each other as a waveguide. FIG. 1 is a sectional view of a high-frequency device and a plan view of a high-frequency member of the device to show a connection structure of a waveguide disclosed in Published Japanese Patent First Publication No. 2007-336299. FIG. 2 is a sectional view of a high-frequency device and a plan view of a high-frequency member of the device to show a connection structure of a waveguide disclosed in Japanese Patent No. 3995929.
As shown in FIG. 1 and FIG. 2, a high-frequency device has two high-frequency members 101 and 102 (or 101 and 103) of which surfaces are attached to each other. The members have respective waveguide portions 104 communicating with each other to form a single waveguide 104. The waveguide 104 is opened on the attaching surfaces of the members. An electromagnetic wave is transmitted through the waveguide 104. To prevent the electromagnetic wave from being leaked from an attaching area between the attaching surfaces of the members, a choke groove 105 is formed in the member 102 so as to surround the waveguide portion 104 of the member 102 (see FIG. 1) through a portion of the member 102, or two choke grooves 106 are formed in the member 103 so as to face the waveguide portion 104 of the member 102 through a portion of the member 103 (see FIG. 2). Each choke groove is placed away from the opened end of the waveguide portion 104 by λ/4 (λ denotes the free space wavelength of the electromagnetic wave) and has the depth of λ/4.
With this structure, even when an opened space is formed between the attached surfaces of the members 101 and 102 (or 101 and 103), an inner wall of the member 102 (or 103) surrounding the waveguide 104 can be treated as an electric short point. Therefore, a high frequency device having the members 101 and 102 (or 101 and 103) can prevent the electromagnetic wave from being leaked from the opened space between the members. Especially, as compared with the choke grooves 106 imperfectly surrounding the waveguide 104, the choke groove 105 surrounding the waveguide 104 in all directions can reliably prevent the leakage of the wave.
However, when a single choke groove is formed in a high-frequency member so as to surround an open end of the waveguide 104 of the member, it is troublesome to form the high frequency device with the waveguide 104 surrounded by the choke groove.
Especially, when a choke groove is formed in a plate-shaped member with a waveguide portion, the member is initially punched to form a choke hole penetrating through the member in its thickness direction, and one opened end of the choke hole is covered with a dielectric substrate having a printed ground pattern to form a choke groove from the choke hole.
However, because the choke groove surrounds the waveguide portion through a wall portion of the member, it is required to support the wall portion by a supporting member until the choke hole is covered with the dielectric substrate.
Therefore, it is difficult to form the choke groove which surrounds the waveguide portion in all directions in an attaching area between high-frequency members attached to each other. That is, a portion of the high-frequency member inevitably remains between ends of the choke groove, and the electromagnetic wave is leaked through the portion of the high-frequency member. In this case, the transmission efficiency of the waveguide for the electromagnetic wave is lowered, and isolation of a first waveguide from a second waveguide adjacent to the first waveguide is degraded.